1. Field of the Invention
This invention relates generally to video-on-demand systems, and more particularly to an improved system for controlling the use of video programs that have been down-loaded from a central station and stored at a customer's site.
2. Description of the Prior Art
There have been a number of proposals for so-called video-on-demand systems. In certain of these proposals, a customer who wants to view a particular video program (e.g., a movie, a video game, or printed text material) will contact a central station and request a program, which will be down-loaded, at high speed, and stored at the customer's site, for later viewing.
U.S. Pat. No. 4,506,387, which is incorporated herein by reference, discloses a programming-on-demand cable system which allows any one of a plurality of individual users to request anyone of a plurality of video programs they wish to view from a library of programs, and permits the requested program to be available for viewing on a conventional television set at the user's location following a request initiated by the user. Each program is preprogrammed in a memory device selectable by a host computer at a central data station in response to an address signal transmitted from the user. The host computer in conjunction with other electronics transmits the video program at a high non-real-time rate over a fiber optic line network to a data receiving station at the user's location. The data receiving station then converts the received optical data back to electrical data and stores it for subsequent real-time transmission to the user's television set. The system permits the user to view any one of a number of programs transmitted on a non-real-time basis, and also allows the user to store tile transmitted program at his data receiving station for an indefinite period of time for viewing at a later date. In this system, however, there is no provision to limit the use a customer may make of a down-loaded program.
U.S. Pat. No. 5,046,090, discloses a video system in which programs are down-loaded and stored. Video programs are rendered unintelligible, e.g. scrambled, by any analog or digital method, and are made intelligible, e.g., descrambled, using random digital codes located in fields. The random digital keys are themselves encrypted, and decrypted by a one or more key obtained from a database located at a remote central facility, along with user-specific information at the time of viewing. Obviously, this system is relatively complex and requires a data link to the remote central facility in order to obtain decryption data.
Similarly, U.S. Pat. No. 5,051,822, discloses a digital, interactive communication system designed to provide a plurality of remote subscribers with any one of a plurality of stored video games or like software packages through the use of a home computing assembly maintained within the subscriber's home and structured to display video as well as generating audio on a standard television receiver and further incorporating the ability to utilize contemporary video gaming control devices for subscriber program interaction. A bi-directional communication link is established over the telephone lines between the home computing assembly and the central remote game storage center wherein the software programs are transmitted as a modulated carrier to the subscriber. Program selection is controlled by a remote game storage center executive software program. Automatic billing is performed by computing equipment maintained in the remote game storage center and transmitted to a headquarters.
Thus, it will be appreciated that the prior art proposals for controlling down-loaded video data are complex and not altogether suitable for widespread commercial use.